The Oldest Mountain range in the United States are the Appalachian Mountains. They consist of Taconic Orogeny (Ordovician);Acadian Orogeny (Devonian);Caledonian Orogeny
(Silurian); Allegheny Orogeny (Pennsylvanian & Permian). They are located in Eastern North America.
(Silurian); Allegheny Orogeny (Pennsylvanian & Permian). They are located in Eastern North America.